--- a
+++ b/src/features/char_distance_feature.py
@@ -0,0 +1,46 @@
+# Base Dependencies
+# ----------------
+import numpy
+
+# Local Dependencies
+# ------------------
+from models import RelationCollection
+
+# 3rd-Party Dependencies
+# ----------------------
+from sklearn.base import BaseEstimator
+
+
+class CharDistanceFeature(BaseEstimator):
+    """
+    CharDistanceFeature
+
+    Computes the number of characters between the two entities of a relation.
+    
+    Source: 
+        Alimova and Tutubalina (2020) - Multiple features for clinical relation extraction: A machine learning approach
+    """
+
+    def __init__(self):
+        pass
+
+    def get_feature_names(self, input_features=None):
+        return ["char_dist"]
+
+    def create_character_distance_feature(
+        self, collection: RelationCollection
+    ) -> numpy.array:
+        features = []
+        for r in collection.relations:
+            features.append([len(r.middle_context)])
+
+        return numpy.array(features)
+
+    def fit(self, x: RelationCollection, y=None):
+        return self
+
+    def transform(self, x: RelationCollection) -> numpy.array:
+        return self.create_character_distance_feature(x)
+
+    def fit_transform(self, x: RelationCollection, y=None) -> numpy.array:
+        return self.create_character_distance_feature(x)